I think we're actually for the most part in agreement.

Please note that the original question posited that the watches would be kept in storage and operated at least once per three months. I agree that hot conditions can destroy lubricants very quickly and also that occasional use is required to keep lubricants in good condition; however, I did not address those issues in my response because the original question took care of them.

There are two processes that cause a lubricant to lose its effectiveness: chemical degradation and physical wear caused by motion or rubbing. My point was that I had been told the chemical degradation process took about 15 years. It is my opinion that if the watch is kept running constantly, the physical wear destroys the lubricant before chemical degradation becomes relevant. However, if the watch is run infrequently, so that physical wear is not a major consideration, then chemical degradation becomes the limiting factor on lubricant life.

Experiment in progress right now: I just received a watch that is about eight years old and clearly has received very little use. It will be interesting to see whether it requires service over the next few months.